CN213614523U - Reciprocating saw - Google Patents

Abstract

A reciprocating saw includes a housing, a motor, and a drive mechanism. The motor is configured to operate in a forward mode and a reverse mode. The forward mode corresponds to the motor rotating in a first rotational direction. The reverse mode corresponds to the motor rotating in a second rotational direction, which is opposite the first rotational direction. The drive mechanism includes: driven gear, connecting rod, output shaft and counter weight. The driven gear is adapted to be rotated by the motor and has an upper portion and a lower portion. The output shaft is adapted to reciprocate through a cutting stroke and a return stroke. The weight is connected to the driven gear to rotate together with the driven gear. When the motor is operating in the forward mode, the counterweight moves through an upper portion of the driven gear during a cutting stroke of the output shaft and moves through a lower portion of the driven gear during a return stroke of the output shaft.

Description

Reciprocating saw

Technical Field

The present invention relates to a power tool, and more particularly to a reciprocating saw.

Background

Power tools include different types of transmission mechanisms to perform work. Power tools having reciprocating drives typically include counterweights to balance the forces generated by an output member (e.g., a saw blade) during reciprocating motion. However, due to the orientation of the counterweight within the power tool, the movement of the counterweight may create inertia that tends to move the power tool away from the workpiece as the power tool operates.

SUMMERY OF THE UTILITY MODEL

In a first aspect, the present invention provides a reciprocating saw including a housing and a motor disposed within the housing. The electric motor is configured and adapted to operate in a forward mode and a reverse mode. The forward mode corresponds to the motor rotating in a first rotational direction, and the reverse mode corresponds to the motor rotating in a second rotational direction, which is opposite the first rotational direction. The reciprocating saw also includes a drive mechanism disposed within the housing and connected to the motor. The drive mechanism includes a driven gear adapted to be rotated by the motor. The driven gear is vertically oriented within the housing and has an upper portion and a lower portion. The driving mechanism further includes a connecting rod connected to the driven gear to convert a rotational motion of the driven gear into a reciprocating motion; and an output shaft connected to the connecting rod to reciprocate through a cutting stroke and a return stroke relative to the housing. The output shaft is configured to support a tool element. The drive mechanism also includes a weight connected to the driven gear for rotation therewith. When the motor is operating in the forward mode, the counterweight moves through an upper portion of the driven gear during a cutting stroke of the output shaft and moves through a lower portion of the driven gear during a return stroke of the output shaft.

In one embodiment of the first aspect, when the motor is operating in the reverse mode, the counterweight moves through a lower portion of the driven gear during a cutting stroke of the output shaft and moves through an upper portion of the driven gear during a return stroke of the output shaft.

In one embodiment of the first aspect, the reciprocating saw further comprises a rotational direction reversing switch connected to the motor, wherein the rotational direction reversing switch is operable to selectively switch the motor between a forward mode and a reverse mode.

In one embodiment of the first aspect, the rotation direction reversal switch is a manual switch supported by the housing.

In one embodiment of the first aspect, the driven gear is adapted to be rotated about the central axis by the electric motor, and wherein the direction of rotation of the driven gear about the central axis will be reversed when the electric motor is switched between the forward mode and the reverse mode.

In one embodiment of the first aspect, the counterweight comprises: a connecting portion connected to the link; and a weight portion including a front edge, a rear edge, and a curved outer periphery matching a circumference of the driven gear. The curved periphery extends more than 90 degrees between the front edge and the rear edge.

In one embodiment of the first aspect, the housing includes a battery support portion. The motor is adapted to rotate about a motor axis. The motor axis extends through the center of the driven gear to divide the driven gear into upper and lower portions. The output shaft and the upper portion of the driven gear are located on the same side of the motor shaft, and the battery support portion and the lower portion of the driven gear are located on the same side (the other side) of the motor shaft.

In a second aspect, the present invention provides a reciprocating saw including a housing and a motor disposed within the housing. The electric motor includes a pinion gear and is configured and adapted to operate in a forward mode and a reverse mode. The forward mode corresponds to the motor rotating in a first rotational direction, and the reverse mode corresponds to the motor rotating in a second rotational direction, which is opposite the first rotational direction. The reciprocating saw further includes a rotational direction reversing switch supported by the housing and connected to the motor. The rotational direction reverse switch is operable to selectively switch the motor between a forward mode and a reverse mode. The reciprocating saw also includes a drive mechanism disposed within the housing and connected to the motor. The drive mechanism includes a driven gear engaged with the pinion gear and adapted to be rotated by the motor. The driven gear is vertically oriented within the housing. The driving mechanism further includes a connecting rod connected to the driven gear to convert a rotational motion of the driven gear into a reciprocating motion; and an output shaft connected to the connecting rod to reciprocate with respect to the housing. The output shaft is configured to support a tool element. The drive mechanism also includes a weight connected to the driven gear for rotation therewith.

In one embodiment of the second aspect, the driven gear has an upper portion and a lower portion. When the motor is operating in the forward mode, the counterweight moves through an upper portion of the driven gear during a cutting stroke of the output shaft and moves through a lower portion of the driven gear during a return stroke of the output shaft.

In one embodiment of the second aspect, when the motor is operating in the reverse mode, the counterweight moves through a lower portion of the driven gear during a cutting stroke of the output shaft and moves through an upper portion of the driven gear during a return stroke of the output shaft.

In one embodiment of the second aspect, the rotational direction reversal switch is manually operable.

In one embodiment of the second aspect, the driven gear is adapted to be rotated about the central axis by the motor. When the motor is switched between the forward mode and the reverse mode, the rotational direction of the driven gear about the center axis is reversed.

In one embodiment of the second aspect, the counterweight comprises: a connecting portion connected to the link; and a weight portion including a front edge, a rear edge, and a curved outer periphery matching a circumference of the driven gear. The curved periphery extends more than 90 degrees between the front edge and the rear edge.

In one embodiment of the second aspect, the housing includes a battery support. The motor is adapted to rotate about a motor axis extending through the center of the driven gear to divide the driven gear into an upper portion and a lower portion. The output shaft and the upper part of the driven gear are positioned on the same side of the motor shaft; and the battery support part is located on the same side (the other side) of the motor shaft as the lower part of the driven gear.

In one embodiment of the second aspect, the pinion gear is disposed between the driven gear and the counterweight.

In a third aspect, the present invention provides a method of operating a reciprocating saw. The reciprocating saw comprises: the device comprises a shell, a motor, a rotation direction reversing switch and a driving mechanism. The electric motor is disposed within the housing and is configured and adapted to operate in a forward mode and a reverse mode. The rotation direction reversing switch is supported by the housing and connected to the motor. A drive mechanism is disposed within the housing and is connected to the motor. The drive mechanism includes a driven gear adapted to be rotated by the motor and oriented vertically within the housing; a connecting rod connected to the driven gear to convert a rotational motion of the driven gear into a reciprocating motion; an output shaft connected to the connecting rod to reciprocate through a cutting stroke and a return stroke relative to the housing, and a weight connected to the driven gear to rotate together with the driven gear. The method comprises the following steps: operating the reciprocating saw in (setting the motor to) a forward mode; actuating a rotational direction reversal switch to place the motor in a reverse mode; and operating the reciprocating saw in (setting the motor to) a reverse mode.

In one embodiment of the third aspect, the method further comprises actuating a rotational direction reversal switch to place the electric motor in a forward mode.

In one embodiment of the third aspect, operating the reciprocating saw with the motor set to the forward mode comprises: the weight is moved through an upper portion of the driven gear during a cutting stroke and through a lower portion of the driven gear during a return stroke.

In one embodiment of the third aspect, operating the reciprocating saw with the motor set to the reverse mode comprises: the weight is moved through a lower portion of the driven gear during a cutting stroke and through an upper portion of the driven gear during a return stroke.

In one embodiment of the third aspect, the method further comprises: operating the reciprocating saw to cut the wood workpiece with the motor set to the forward mode; and/or operating the reciprocating saw to cut the metal workpiece with the motor set to reverse mode.

Other features and aspects of the present invention will become apparent by consideration of the following detailed description and accompanying drawings.

Drawings

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

fig. 1 is a perspective view of a reciprocating saw embodying the present invention.

FIG. 2 is a side view of the reciprocating saw of FIG. 1 with a portion of the housing removed.

FIG. 3 is a top view of the reciprocating saw of FIG. 1 with a portion of the housing removed.

FIG. 4 illustrates a saw blade suitable for use with a reciprocating saw.

Fig. 5 is a graph depicting vertical vibration caused by movement of a weight in one direction.

Fig. 6 is a graph depicting vertical vibration caused by movement of the counterweight in the opposite direction.

Fig. 7 is a perspective view of another reciprocating saw embodying the present invention.

FIG. 8 is a schematic view of a control mechanism of the reciprocating saw of FIG. 7.

Fig. 9 is a graph depicting the cutting time measured when the reciprocating saw of fig. 7 and the conventional reciprocating saw cut wood and metal workpieces.

Detailed Description

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

Fig. 1 to 3 show a power tool 10. In the illustrated embodiment, the power tool 10 is a reciprocating saw. In other embodiments, the power tool 10 may be other types of devices that use reciprocating drive mechanisms, such as jigsaws, knives, hammer drills, and the like.

The illustrated reciprocating saw 10 includes a housing 14, a motor 18 disposed within the housing 14, and a transmission 22 connected to the motor 18 and disposed within the housing 14. As shown in fig. 1, the housing 14 is made up of two half- shells 24A and 24B, the half- shells 24A and 24B being joined together along a plane 25 (fig. 3). In the illustrated embodiment, the half shells 24A and 24B are secured together by threaded fasteners (e.g., screws), but alternatively, the half shells 24A and 24B may be secured together using other suitable connecting means. FIG. 2 illustrates the reciprocating saw 10 with one half shell 24A of the reciprocating saw 10 removed to facilitate displaying the internal components of the reciprocating saw 10 (e.g., the motor 18, the transmission 22, etc.).

Referring to fig. 1, the housing 14 includes a rear portion 26, a front portion 30, and a battery support portion 34. The housing 14 also defines a longitudinal axis 38 (fig. 2), the longitudinal axis 38 extending through the rear portion 26 and the front portion 30. The rear portion 26 includes a D-handle 42 and the front portion 30 includes a grip 46. The D-handle 42 and the grip 46 are configured to be grasped by a user during operation of the reciprocating saw 10. An actuator or trigger 50 is supported by the rear portion 26 at a position adjacent the D-handle 42. The trigger 50 is actuatable by a user to selectively activate the motor 18. In the illustrated embodiment, the trigger 50 is disposed above the longitudinal axis 38, the longitudinal axis 38 generally dividing the housing 14 into upper and lower portions. The shoe 54 extends from the front 30 of the housing 14 and is pivotally connected to the front 30 of the housing 14. The shoe 54 rotates about a pivot axis 56 and facilitates alignment of the reciprocating saw 10 to a workpiece being cut.

A battery support 34 is formed on the rear 26 of the housing 14 and is located below the D-handle 42. In the illustrated embodiment, the battery support 34 is located below the longitudinal axis 38 of the housing 14 when the reciprocating saw 10 is viewed from the perspective shown in FIG. 2. In other embodiments, the battery support 34 may be located elsewhere on the housing 14. The battery support 34 is configured to receive a battery pack (e.g., an 18V lithium ion power tool battery pack) and electrically connect the battery pack to the motor 18. In some other embodiments, the battery pack may have different voltages and/or chemistries. In some other embodiments, the reciprocating saw 10 may include a power cord such that the motor 18 may be powered by an alternating current power source (e.g., a wall outlet, a portable generator, etc.).

As shown in fig. 2, the motor 18 is disposed within the housing 14 between the rear portion 26 and the front portion 30. The motor 18 is also electrically connected to a battery pack (or other suitable power source) through a trigger 50. As shown in fig. 3, the motor 18 includes a motor shaft 58 and an output gear or pinion 62. Referring to fig. 2, the motor shaft 58 defines a central longitudinal axis 70 or motor axis of the motor 18. In the illustrated embodiment, the central longitudinal axis 70 of the motor 18 is generally aligned with or generally coaxial with the longitudinal axis 38 of the housing 14. When activated, the motor 18 rotates the motor shaft 58 and pinion gear 62 about the axis 70 to drive the transmission 22.

As shown in fig. 2 and 3, the transmission 22 is at least partially disposed within the front portion 30 of the housing 14 between the motor 18 and the shoe 54. The illustrated transmission 22 is a slider crank mechanism. The slider-crank mechanism includes a driven gear 74, a connecting rod 78, and an output shaft 82. However, other mechanisms, such as scotch-yoke mechanisms, are also contemplated or used. The driven gear 74 meshes with the pinion gear 62 of the motor 18 and defines a central axis 86, the driven gear 74 rotating about the central axis 86. In the illustrated embodiment, the central axis 86 is perpendicular to the longitudinal axis 38 of the housing 14 and extends between opposite sides of the housing 14 and is parallel to the pivot axis 56 of the shoe 54. More specifically, the central axis 86 is perpendicular to the plane 25 along which the half shells 24A and 24B of the housing 14 are joined. The driven gear 74 is thus positioned vertically within the housing 14.

The longitudinal axis 38 of the housing 14 and the central axis 70 of the motor 18 extend through the center of the gear 74 (i.e., through the central axis 86) to divide the gear 74 into a first or upper portion 90 and a second or lower portion 94. In the illustrated embodiment, the upper portion 90 of the driven gear 74 and the output shaft 82 and the trigger 50 are located on the same side of the longitudinal axis 38, while the lower portion 94 of the driven gear 74 and the battery support portion 34 are located on the same side (the other side) of the longitudinal axis 38. In other embodiments, the output shaft 82 may be located on opposite sides of the longitudinal axis 38 such that the lower portion 94 of the driven gear 74 and the output shaft 82 are located on the same side of the longitudinal axis 38. It should be appreciated that the upper portion 90 and lower portion 94 of the driven gear 74 will change during operation of the transmission 22 as the driven gear 74 will rotate. The terms "upper" and "lower" are merely illustrative terms to help describe the volume of space above axes 38 and 70 and the volume of space below axes 38 and 70 occupied by different portions of gear 74 at any given time. The actual portion of gear 74 that is described as "upper" or "lower" at one particular time may be different than the actual portion of gear 74 that is described as "lower" or "upper" at another particular time.

The connecting rod 78 or drive arm includes a first end connected to the driven gear 74 by a crank pin 98 and a second end connected to the output shaft 82 by a pivot pin 102. The crank pin 98 is offset from the central axis 86 of the driven gear 74 such that the crank pin 98 moves about the central axis 86 as the gear 74 rotates. When the first end of the link 78 moves with the driven gear 74, the second end of the link 78 pushes and pulls the output shaft 82 in a reciprocating motion. The crank pin 98 allows the link 78 to pivot vertically relative to the driven gear 74, while the pivot pin 102 allows the link 78 to pivot vertically relative to the output shaft 82.

The output shaft 82 or spindle reciprocates within the front portion 30 of the housing 14 generally along a spindle axis 106. In the illustrated embodiment, the spindle axis 106 is generally parallel to the longitudinal axis 38 of the housing 14 and is disposed above the longitudinal axis 38 of the housing 14. The rotational motion of the motor 18 is thus converted into linear reciprocating motion of the output shaft 82 through the driven gear 74 and the connecting rod 78.

The motor axis 70 and the spindle axis 106 together define a plane. Driven gear 74 is positioned vertically within housing 14, with gear 74 rotating about an axis that is perpendicular to the plane defined by motor axis 70 and spindle axis 106 (i.e., central axis 86). In the illustrated embodiment, the plane defined by the motor axis 70 and the spindle axis 106 is the same plane as the plane 25 (fig. 3) along which the half shells 24A and 24B are joined together. In other embodiments, one or both of the motor axis 70 and the spindle axis 106 may be offset from the plane 25 but still parallel to the plane 25.

With continued reference to FIG. 2, a toolholder 110 is coupled to the end of the output shaft 82 opposite the connecting rod 78. The tool holder 110 receives and secures a saw blade 112 (fig. 4) or other tool component to secure the saw blade 112 or other tool component to the output shaft 82 for reciprocal movement with the output shaft 82. The output shaft 82 supports the saw blade 112 such that during operation of the reciprocating saw 10, the transmission mechanism 22 moves the blade 112 through a cutting stroke when the output shaft 82 is pulled by the linkage 78 from the extended position to the retracted position, and the transmission mechanism 22 moves the blade 112 through a return stroke when the output shaft 82 is pushed by the linkage 78 from the retracted position to the extended position.

The illustrated drive mechanism 22 also includes a counterweight 114. The counterweight 114 helps balance the forces generated by the output shaft 82 and the attached saw blade during reciprocation. In the illustrated embodiment, the counterweight 114 and the driven gear 74 are separate components, but alternatively, the counterweight 114 and the driven gear 74 may be integrally formed as a single component. The illustrated counterweight 114 includes a connecting portion 118 and a weight portion 122. The connecting portion 118 is connected to the connecting rod 78 by the crank pin 98. Guide pins 126 also extend from the connecting portion 118 and engage the inner surface of the housing 14. The guide pin 126 supports the counterweight 114 within the housing 14 and defines an axis of rotation 130 of the counterweight 114. In the illustrated embodiment, the rotational axis 130 of the counterweight 114 and the central axis 86 of the driven gear 74 are generally coaxial such that the counterweight 114 and the driven gear 74 rotate about the same axis. Similar to driven gear 74, counterweight 114 is thus also positioned vertically within housing 14. In the illustrated embodiment, the axis of rotation 130 intersects the motor axis 70 and is perpendicular to the motor axis 70.

The weight portion 122 extends from the connecting portion 118 and includes most of the weight of the counterweight 114. Thus, movement of the weight 122 in a direction opposite to the movement of the output shaft 82 will tend to balance the forces generated when the saw blade reciprocates in the fore-aft direction. In the illustrated embodiment, the weight portion 122 has a generally semi-circular shape to mate with the circular shape and contour of the driven gear 74. That is, the shape and size of the counterweight 114 is configured such that the counterweight 114 does not protrude outside of the vertical footprint defined by the driven gear 74 (or only partially protrudes outside of the vertical footprint). Such a configuration may reduce the amount of space required within the housing 14 to accommodate the counterweight 114. In other embodiments, the weight 122 may have other suitable shapes and configurations.

As the driven gear 74 rotates and drives the crank pin 98, the weight portion 122 of the counterweight 114 moves in a direction substantially opposite to the direction of movement of the output shaft 82 to balance the inertial forces generated by the output shaft 82 and the attached saw blade. In particular, as shown in fig. 2, when the output shaft 82 is in the extended position, the weight portion 122 of the counterweight 114 is in a first position (e.g., relatively close to the motor 18 and relatively far from the output shaft 82). When the output shaft 82 is in the retracted position, the weight portion 122 of the counterweight 114 rotates to a second position (e.g., relatively closer to the output shaft 82 and relatively farther from the motor 18).

In the illustrated embodiment, the counterweight 144 rotates in a clockwise direction R (when the reciprocating saw 10 is viewed from the perspective shown in fig. 2) about the rotational axis 130 along the path P between the first position and the second position. That is, during the cutting stroke of the output shaft 82, the weight portion 122 of the counterweight 114 moves generally above the longitudinal axis 38 of the housing 14, through the upper portion 90 of the driven gear 74, from the first position to the second position. Conversely, on the return stroke of the output shaft 82, the weight portion 122 of the counterweight 114 moves generally below the longitudinal axis 38 of the housing 14, through the lower portion of the driven gear 74, from the second position to the first position. In other words, at the end of the return stroke and the beginning of the cutting stroke, as the weight 122 of the counterweight 114 moves through the second half of the path P (i.e., the half of the path P near the rear 26 of the housing 14), the weight 122 moves generally in an upward direction (from the perspective shown in fig. 2) and toward the spindle axis 106. At the end of the cutting stroke and the beginning of the return stroke, as the weight portion 122 of the counterweight 114 moves through the front half of the path P (i.e., the half of the path P near the front portion 30 of the housing 14), the weight portion 122 moves generally in a downward direction (from the perspective shown in fig. 2) and away from the spindle axis 106. This movement of the counterweight 114 causes the forward end of the saw 10 to tend to move into the workpiece (downwardly in fig. 2) as the cutting stroke begins.

Since the counterweight 114 is connected to the driven gear 74 by the crankpin 98, the counterweight 114 does not actually move relative to the gear 74. Conversely, the counterweight 114 and the driven gear 74 rotate through the path P. As noted above, the terms "upper" and "lower" of driven gear 74 are used to indicate the amount of space occupied by different portions of gear 74 during operation of transmission 22.

The configuration of the counterweight 114 and the driven gear 74 improves the cutting performance of the reciprocating saw 10 as compared to rotation of the counterweight 114 in the opposite direction (e.g., counterclockwise when viewing the reciprocating saw 10 from the perspective shown in FIG. 2). In particular, the weight 122 of the counterweight 114 tends to move the saw 10 in the cutting direction during the non-cutting stroke, which helps drive the reciprocating saw 10 and the saw blade 112 into the workpiece at the beginning of the next cutting stroke. Conversely, if the counterweight 114 is rotated in the opposite direction, the reciprocating saw 10 and blade 112 will tend to move away from the workpiece at the beginning of the next cutting stroke. By rotating the counterweight 114 in the clockwise direction R, the user can more easily begin cutting into the workpiece and the time required to cut the workpiece is greatly reduced.

Fig. 5 is a graph illustrating the vibration generated by the reciprocating saw 10 in the vertical direction during operation, and fig. 6 is a graph illustrating the vibration generated by the reciprocating saw including the counterweight rotating in the opposite direction to the counterweight 114 described above. As shown in fig. 5, the speed of the saw 10 lags behind its acceleration. Thus, the speed of the counterweight 114 of the clockwise rotating saw 10 is downward at the end of the return stroke and the beginning of the cutting stroke. This downward speed creates a force that drives the saw 10 (more specifically, the saw blade 112) into the workpiece to begin cutting the workpiece. Conversely, as shown in FIG. 6, the speed of the counterclockwise rotating saw 10 will generate a force that will drive the saw 10 and blade 112 upward at the end of the return stroke and the beginning of the cutting stroke. If the arrangement shown in fig. 6 is used, at the beginning of each cut, both the saw and the blade are pulled away from the workpiece, which can cause the blade to "jump" and reduce the cutting efficiency.

Referring to FIG. 7, in some embodiments, the reciprocating saw 10 further includes a rotational direction reversing switch 134 for reversing the rotational direction of the motor 18. Reversing the direction of rotation of motor 18 reverses counterweight 114 along path P (i.e., changes direction between clockwise direction R and counterclockwise direction). A rotational direction reverse switch 134 is supported by the housing 14 and is user-actuatable to selectively reconfigure the motor 18 between a forward mode (corresponding to rotation of the counterweight 114 in the clockwise direction R) and a reverse mode (corresponding to rotation of the counterweight 114 in the opposite, counterclockwise direction). In this manner, the user may select a cutting mode (i.e., forward or reverse, corresponding to clockwise or counterclockwise rotation of the counterweight 114) that is most appropriate for the particular characteristics (e.g., material strength, hardness, etc.) of the workpiece to be cut, thereby improving the cutting performance of the reciprocating saw 10.

In the illustrated embodiment, the reversing switch 134 is supported by the rear portion 26 above the D-handle 42. In other embodiments, the reversing switch 134 may be supported at other areas of the housing 14, such as at the handle 42, or near the battery support 34. In some embodiments, the reverse switch 134 may be configured as a slide switch and may be actuated between a forward position corresponding to a forward mode (i.e., the counterweight 114 is rotated in the clockwise direction R along the path P of fig. 2) and a reverse position corresponding to a reverse mode (i.e., the counterweight 114 is rotated in the counterclockwise direction). In other embodiments, the reversing switch 134 may be a dial, button, or other suitable actuator. The housing 14 may include indicia (e.g., letters or symbols) adjacent the reversing switch 134 to help identify the current position of the switch 134, and thus the mode of the motor 18.

FIG. 8 is a block diagram of the control mechanism 138 associated with the reciprocating saw 10. The control mechanism 138 includes a controller 142, the controller 142 being electrically and/or communicatively connected to various components of the reciprocating saw 10. For example, the controller 142 is connected to the motor 18, a power source 146 (e.g., a battery pack or power cord as discussed above), the trigger 50, a speed switch 150 for adjusting the rotational speed of the motor 18, and the rotational direction reversal switch 134.

The controller 142 includes, among other things, a processing unit 154 (e.g., a microprocessor, microcontroller, or another suitable programming device) and a memory 158. Memory 158 may include, for example, a program storage area and a data storage area. The processing unit 154 may be connected to the memory 158 to execute software instructions that can be stored in a random access memory of the memory 158 (e.g., during execution), a read only memory of the memory 158 (e.g., in a more permanent manner), or another non-transitory computer readable medium (e.g., another memory or an optical disk). For example, actuating the reverse switch 134 may reverse the polarity of the motor 18 via the controller 142.

As discussed above, the placement of the counterweight 114 and the driven gear 74 can affect the cutting performance of the reciprocating saw 10. That is, in operation of the reciprocating saw 10, at the beginning of a cutting stroke, when the counterweight 114 is rotated in a clockwise direction along the path P (when the reciprocating saw 10 is viewed from the perspective shown in fig. 2), the weight portion 122 of the counterweight 114 tends to drive the reciprocating saw 10 and the saw blade 112 into a workpiece. Conversely, at the beginning of the cutting stroke, when the counterweight 114 is rotated in the opposite direction (counterclockwise when viewing the reciprocating saw 10 from the perspective shown in FIG. 2), the reciprocating saw 10 and the saw blade 112 may tend to move away from the workpiece.

Additionally, when the saw 10 is operated in the forward mode, the clockwise rotation of the counterweight 114 tends to increase the proportion of the vibrations experienced by the saw blade 112 in the vertical direction (which is generally perpendicular to the forward and rearward directions along which the saw blade 112 reciprocates). The forward mode of operation of the saw 10 tends to improve cutting performance on relatively softer materials (e.g., wood) as compared to operation in the reverse mode. Conversely, when the saw 10 is operated in the reverse mode, the counterclockwise rotation of the counterweight 114 tends to reduce the proportion of vibration experienced by the blade 112 in the vertical direction. Operation of the saw 10 in the reverse mode tends to improve cutting performance on relatively harder materials (e.g., metals) as compared to operation in the forward mode.

FIG. 9 is a graph illustrating the cut times recorded for a reciprocating saw 10 operating in a forward mode, a reciprocating saw 10 operating in a reverse mode, and a conventional reciprocating saw 162 configured to operate in only one cutting mode. For each saw 10, 162, the graph compares the cutting time recorded for cutting a sample workpiece made of wood and a sample workpiece made of metal. Specifically, the cutting time for cutting a 2 inch by 12 inch White Fir wood (White Fir chamber) panel and a 2 inch diameter metal pipe was recorded.

As shown in fig. 9, the reciprocating saw 10 operating in the forward mode records the fastest cutting time for cutting the sample wood workpiece as compared to the reciprocating saw 10 operating in the reverse mode and the conventional reciprocating saw 162. Further, when operating in the reverse mode, the saw 10 records a cut time for cutting the sample wood workpiece that is only slightly faster than the cut time of the conventional reciprocating saw 162. In contrast, the reciprocating saw 10 operating in the forward mode records the slowest cutting time when cutting a sample metal workpiece. However, the reciprocating saw 10 operating in the reverse mode records the fastest cutting time for cutting the sample metal workpiece as compared to the reciprocating saw 10 operating in the forward mode and the conventional reciprocating saw 162.

By selectively reversing the motor between the forward cutting mode and the reverse cutting mode depending on which mode may be more appropriate for the characteristics of a particular workpiece, the reciprocating saw 10 exhibits improved cutting speeds for both wood and metal workpieces as compared to the conventional reciprocating saw 162.

Although the invention has been described with reference to certain preferred embodiments, various changes and modifications may be made within the scope of one or more independent aspects of the invention. Various features and advantages of the invention are set forth in the following claims.

Claims (15)

1. A reciprocating saw, characterized in that said reciprocating saw comprises:

a housing;

a motor disposed within the housing and configured to operate in a forward mode and a reverse mode, the forward mode corresponding to the motor rotating in a first rotational direction and the reverse mode corresponding to the motor rotating in a second rotational direction, the second rotational direction being opposite the first rotational direction;

a drive mechanism disposed within the housing and connected to the motor, the drive mechanism comprising:

a driven gear adapted to be rotated by the motor, the driven gear being vertically oriented within the housing and having an upper portion and a lower portion;

a connecting rod connected to the driven gear to convert a rotational motion of the driven gear into a reciprocating motion;

an output shaft connected to the link to reciprocate through a cutting stroke and a return stroke relative to the housing, the output shaft configured to support a tool element, an

A weight connected to the driven gear to rotate together with the driven gear;

wherein when the motor is operating in the forward mode, the counterweight moves through the upper portion of the driven gear during the cutting stroke of the output shaft and through the lower portion of the driven gear during the return stroke of the output shaft.

2. The reciprocating saw as defined in claim 1, wherein said counterweight moves through said lower portion of said driven gear during said cutting stroke of said output shaft and through said upper portion of said driven gear during said return stroke of said output shaft when said motor is operating in said reverse mode.

3. The reciprocating saw as defined in claim 1 or 2, further comprising a rotational direction reversing switch connected to said motor, wherein said rotational direction reversing switch is operable to selectively switch said motor between said forward mode and said reverse mode.

4. The reciprocating saw as defined in claim 3, wherein said rotational direction reversing switch is a manual switch supported by said housing.

5. The reciprocating saw as defined in claim 1 or 2, wherein said driven gear is adapted to be rotated by said motor about a central axis, and wherein a direction of rotation of said driven gear about said central axis will be reversed when said motor is switched between said forward mode and said reverse mode.

6. The reciprocating saw as defined in claim 1 or 2, wherein said counterweight includes:

a connecting portion connected to the link; and

a weight including a front edge, a rear edge, and a curved periphery that matches a circumference of the driven gear, wherein the curved periphery extends more than 90 degrees between the front edge and the rear edge.

7. The reciprocating saw of claim 1 or 2, wherein the housing includes a battery support; wherein the motor is adapted to rotate about a motor axis extending through the center of the driven gear to divide the driven gear into an upper portion and a lower portion; wherein the output shaft is located on the same side of the motor shaft as the upper portion of the driven gear; and wherein the battery support portion is located on the same side of the motor shaft as the lower portion of the driven gear.

8. A reciprocating saw, characterized in that said reciprocating saw comprises:

a housing;

a motor disposed within the housing, the motor including a pinion gear and being configured and adapted to operate in a forward mode and a reverse mode, the forward mode corresponding to the motor rotating in a first rotational direction and the reverse mode corresponding to the motor rotating in a second rotational direction, the second rotational direction being opposite the first rotational direction;

a rotational direction reverse switch supported by the housing and connected to the motor, the rotational direction reverse switch operable to selectively switch the motor between the forward mode and the reverse mode;

a drive mechanism disposed within the housing and connected to the motor, the drive mechanism comprising:

a driven gear engaged with the pinion gear and adapted to be rotated by the motor, the driven gear being vertically oriented within the housing;

a connecting rod connected to the driven gear to convert a rotational motion of the driven gear into a reciprocating motion;

an output shaft connected to the link for reciprocating movement relative to the housing, the output shaft configured to support a tool element, an

A weight connected to the driven gear to rotate together with the driven gear.

9. The reciprocating saw as defined in claim 8, wherein said driven gear has an upper portion and a lower portion; and wherein, when the motor is operating in the forward mode, the counterweight moves through the upper portion of the driven gear during the cutting stroke of the output shaft and through the lower portion of the driven gear during the return stroke of the output shaft.

10. The reciprocating saw as defined in claim 9, wherein said counterweight moves through said lower portion of said driven gear during said cutting stroke of said output shaft and through said upper portion of said driven gear during said return stroke of said output shaft when said motor is operating in said reverse mode.

11. The reciprocating saw as defined in any one of claims 8 to 10, wherein said rotational direction reversing switch is manually operable.

12. The reciprocating saw as defined in any one of claims 8 to 10, wherein said driven gear is adapted to be rotated about a central axis by said motor, and wherein a direction of rotation of said driven gear about said central axis will be reversed when said motor is switched between said forward mode and said reverse mode.

13. The reciprocating saw as defined in any one of claims 8 to 10, wherein said counterweight includes:

a connecting portion connected to the link; and

a weight including a front edge, a rear edge, and a curved periphery that matches a circumference of the driven gear, wherein the curved periphery extends more than 90 degrees between the front edge and the rear edge.

14. The reciprocating saw as defined in claim 8, wherein said housing includes a battery support; wherein the motor is adapted to rotate about a motor axis extending through the center of the driven gear to divide the driven gear into an upper portion and a lower portion; wherein the output shaft is located on the same side of the motor shaft as the upper portion of the driven gear; and wherein the battery support portion is located on the same side of the motor shaft as the lower portion of the driven gear.

15. The reciprocating saw as defined in any one of claims 8 to 10, wherein said pinion gear is disposed between said driven gear and said counterweight.

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